1. Field of the Invention
The present invention relates to the preservation of wood and, in particular, the preservation of wood by means of chromated copper arsenate solutions.
2. Brief Description of the Prior Art
The preservation of wood under pressure with various chromated copper arsenate (CCA) solutions is well known in the art. Such solutions are described, for example, in the American Wood Preservers' Association Book of Standards (1987), Section P5-86, pages 2 and 3.
Fixation is a process whereby CCA solutions undergo reaction with wood to be relatively insoluble. The process involves the reaction of hexavalent chromium with wood to give trivalent chromium and a corresponding reduction in acidity, thereby producing insoluble CCA-wood compounds. The reaction of hexavalent chromium with wood is slow at ambient temperatures, typically requiring several days for completion. The reaction can be accelerated by heat. In order to enhance fixation of CCA-wood commercially, a variety of heating techniques have been developed which include kiln drying, steam treatment, and microwave treatment. A disadvantage, however, of such techniques is that they require considerable capital investment and are time consuming. It is, therefore, the object of the present invention to provide a means for fixing aqueous CCA chemicals in wood both quickly and inexpensively.